A class of 7-azaindole compounds, their preparation, and their application in the prevention and control of plant viral and fungal diseases.

Abstract

This invention relates to 7-azaindole compounds I-1–I-5, their preparation methods, and their applications in the prevention and control of plant viral and fungal diseases. This invention provides a series of 7-azaindole compounds, develops efficient synthetic methods for these compounds, and discovers their antiviral and antipathogenic activities, laying the foundation for the synthesis and bioactivity research of these compounds. The 7-azaindole compounds I-1–I-5 of this invention exhibit antiviral activity, inhibiting tobacco mosaic virus, and also demonstrate broad-spectrum antipathogenic activity.

Description

Technical Field

[0003] This invention relates to a class of 7-azaindole compounds, their preparation, and their application in the prevention and control of plant viral and bacterial diseases, belonging to the field of agricultural protection technology. Background Technology

[0005] Plant viral diseases can cause crop yield reductions of 20% to total crop failure, resulting in over $60 billion in economic losses globally each year, earning them the nickname "plant cancer." These diseases not only severely impact crop yield and quality but can also trigger a chain of economic and ecological problems. The irrational use of antiviral agents has led to a series of environmental, agricultural, and human health issues, making it urgent to find suitable, novel, highly effective, and low-risk pesticides. Naturally derived biomimetic pesticides, spearheaded by natural products, are gradually becoming an important direction for new pesticide development [Cur. Sci. 2009, 96, 753–754, Phyto. Rev.2015, 14, 299–315]. Marine alkaloids possess unparalleled skeletal diversity and novelty compared to terrestrial alkaloids [J. Nat. Prod. 2020, 83, 770–803], exhibit a wider range of pharmacological activities and unique mechanisms of action, and often demonstrate a rich variety of physiological activities. They are widely used in the pharmaceutical, health product, fine chemical, and cosmetic industries.

[0006] Marine sponges are considered a rich source of bioactive secondary metabolites, exhibiting unprecedented chemical structural diversity [Nat. Prod. Rep. 2011, 38, 172–188]. Hyrtimomine, a novel bisindole alkaloid extracted from Okinawa sponges, has attracted considerable interest from pharmaceutical enthusiasts due to its unique chemical structure and rich bioactivity. However, the complex molecular structure of hyrtimomine alkaloid (structural formula 1) limits its applications. Structural simplification of natural products is an effective strategy for biomimetic drug research. Based on this, we optimized the structure of the natural product hyrtimomine and designed and synthesized a series of 7-azaindole compounds. We investigated the antiviral activity and structure-activity relationship of the synthesized compounds against tobacco mosaic virus and systematically explored the antibacterial activity of the target compounds. Currently, systematic research on the application of hyrtimomine and its derivatives in plant disease control, especially in antiviral and antifungal activities, is still lacking, and related structural optimization and activity evaluation have not been systematically reported.

[0007]

[0008] Structural Formula 1 Summary of the Invention

[0010] To address the shortcomings of existing technologies, this invention provides a class of 7-azaindole compounds, their preparation method, and their application in the prevention and control of plant viral and fungal diseases. The 7-azaindole compounds of this patent exhibit excellent antiviral and antifungal activity against plant viruses and pathogens.

[0011] The 7 azaindole compounds of this invention are compounds shown in general formula I, with specific structures as shown in I-1 to I-5 below (structural formula II), where R is a group shown in the structure I-1 to I-5.

[0012]

[0013] Structural Form 2

[0014] The preparation method of the above compounds I-1-I-5:

[0015] Prepared according to the method shown in Equation 1, in an acetonitrile solution of sodium hydroxide, 80 o Under C conditions, compounds 1 and 2 undergo nucleophilic substitution to give the corresponding compounds I-1-I-5.

[0016]

[0017] Equation 1

[0018] In Equation 1 above, R is the substituent shown in the I-1-I-5 structure; raw materials 1 and 2 were purchased directly from Bid Pharmaceutical Technology Co., Ltd.

[0019] The 7-azaindole compounds I-1-I-5 of this invention exhibit outstanding antiviral and antipathogenic activity against plant viruses and pathogens, showing significant inhibitory effects against Tobacco Mosaic Virus (TMV), as well as Tomato Early Blight Fungicide, Rice Blast Fungicide, Pepper Phytophthora, Rapeseed Sclerotinia Germinatus, Cucumber Fusarium Wilt Fungicide, Peanut Brown Spot Fungicide, Apple Ring Spot Fungicide, and Wheat Sheath Blight Fungicide. Detailed Implementation

[0021] The following examples and test results are intended to further illustrate the present invention, but do not imply limitation of the invention.

[0022] Example 1: Synthesis of compounds I-1–I-5

[0023] 5-Bromo-7-azaindole (0.99 g, 5 mmol) was dissolved in 20 mL of ethanol, and sodium hydroxide (0.24 g, 6 mmol) was added. The mixture was then heated to 80 ºC, and the corresponding substituted benzyl bromide (6 mmol) was added dropwise while stirring. The reaction was monitored by TLC until 5-bromo-7-azaindole disappeared. The mixture was cooled to room temperature, and a solid precipitated. The solid was then filtered to give products I-1–I-5.

[0024] I-1: Brown solid, yield of 78%. Mp 117–119 ºC. 1 H NMR (400 MHz, CDCl3) δ 8.35 (d, J = 2.1 Hz, 1H, ArH), 8.02 (d, J = 2.1 Hz, 1H, ArH), 7.41 (d, J = 7.4 Hz, 1H, ArH), 7.32 – 7.27 (m, 3H, ArH), 7.18 (dd, J = 4.7, 2.7Hz, 2H, ArH), 6.41 (d, J = 3.5 Hz, 1H, ArH), 5.45 (s, 2H, CH2). 13 C NMR (100MHz, CDCl3) δ 143.6, 130.9, 129.4, 128.8, 128.8, 128.3, 127.8, 127.5, 99.7,48.1. HRMS (ESI): Calcd for C 14 H 12 BrN2 [M+H] + 287.0178, found 287.0183.

[0025] I-2: Brown solid, yield 75%. Mp 125–127 ºC. 1 H NMR (400 MHz, CDCl3)δ 8.35 (d, J = 2.1 Hz, 1H, ArH), 8.00 (d, J = 2.2 Hz, 1H, ArH), 7.34 – 7.30(m, 2H, ArH), 7.18 (d, J = 3.5 Hz, 1H, ArH), 7.12 (d, J = 8.3 Hz, 2H, ArH), 6.39 (d, J = 3.5 Hz, 1H, ArH), 5.41 (s, 2H, CH2), 1.27 (s, 9H, CH3). 13C NMR(100 MHz, CDCl3) δ 150.8, 143.5, 134.3, 130.8, 129.5, 127.3, 125.7, 122.1,111.7, 99.6, 47.8, 34.6, 31.4. HRMS (ESI): Calcd for C 15 H 14 BrN2 [M+H] + 301.0335, found 301.0339.

[0026] I-3: Yellow solid, yield 74%. M.p. 125–127 ºC. 1 H NMR (400 MHz, CDCl3)δ 8.34 (d, J = 2.1 Hz, 1H, ArH), 8.06 (d, J = 2.1 Hz, 1H, ArH), 7.61 – 7.56(m, 2H, ArH), 7.24 (d, J = 8.5 Hz, 2H, ArH), 7.20 (d, J = 3.5 Hz, 1H, ArH),6.49 (d, J = 3.5 Hz, 1H, ArH), 5.52 (s, 2H, CH2). 13 C NMR (100 MHz, CDCl3) δ146.0, 143.9, 142.8, 132.6, 131.2, 129.2, 127.8, 122.0, 118.6, 112.2, 111.7,100.5, 47.7. HRMS (ESI): Calcd for C 15 H 11 BrN3 [M+H] + 312.0131, found 312.0136.

[0027] I-4: Orange solid, yield 65%. M.p. 101–103 ºC. 1H NMR (400 MHz, CDCl3)δ 8.35 (d, J = 2.1 Hz, 1H, ArH), 8.04 (d, J = 2.1 Hz, 1H, ArH), 7.27 (s, 1H,ArH), 7.25 (s, 1H, ArH), 7.17 (d, J = 3.5 Hz, 1H, ArH), 7.13 (s, 1H, ArH),7.11 (s, 1H, ArH), 6.43 (d, J = 3.5 Hz, 1H, ArH), 5.42 (s, 2H, CH2). 13 C NMR(100 MHz, CDCl3) δ 146.0, 143.7, 135.9, 133.7, 131.0, 129.2, 129.0, 128.8,122.0, 111.9, 100.0, 47.5. HRMS (ESI): Calcd for C 14 H 11 BrClN2 [M+H] + 320.9789,found 320.9793.

[0028] I-5: Yellow solid, yield 43%. M.p. 107–109 ºC. 1 H NMR (400 MHz, CDCl3)δ 8.35 (d, J = 2.1 Hz, 1H, ArH), 8.02 (d, J = 2.0 Hz, 1H, ArH), 7.21 (d, J =6.2 Hz, 2H, ArH), 7.19 – 7.15 (m, 2H, ArH), 7.04 (d, J = 6.3 Hz, 1H, ArH),6.43 (d, J = 3.5 Hz, 1H, ArH), 5.41 (s, 2H, CH2). 13 C NMR (100 MHz, CDCl3) δ143.8, 139.4, 134.7, 131.0, 130.1, 129.2, 128.0, 127.5, 125.5, 122.0, 112.0,100.1, 47.5. HRMS (ESI): Calcd for C 14 H 11 BrClN2 [M+H] + 320.9789, found320.9795.

[0029] Example 2: Determination of activity against tobacco mosaic virus, the determination procedure is as follows:

[0030] 1. Virus purification and concentration determination:

[0031] Virus purification and concentration determination were performed in accordance with the SOP (Standard Operating Procedure) for tobacco mosaic virus prepared by the Bioassay Laboratory of the Institute of Elementsology, Nankai University. The crude virus extract was centrifuged twice with polyethylene glycol, and the concentration was determined. It was then stored at 4 °C for later use.

[0032] 2. Preparation of compound solutions:

[0033] Weigh the original drug, dissolve it in DMF, and prepare a solution of 1 × 10⁻⁶. 5 The stock solution is prepared at µg / mL. Before use, it is diluted to the required concentration with an aqueous solution containing 1‰ Tween-80. The ribavirin preparation used as a control is diluted directly with deionized water.

[0034] 3. In vivo protection:

[0035] Select uniformly growing 3–5 leaf stage *Nicotiana sambac* plants for whole-plant spraying. Each treatment was replicated in triplicate, with a 1‰ Tween-80 aqueous solution used as a control. 24 hours after application, 500-mesh emery was sprinkled on the leaves as an abrasive. Then, using a brush dipped in a 10 µg / mL virus solution, the leaves were gently rubbed twice along the veins, with the palm of the hand supporting the underside of the leaf during inoculation. Immediately after inoculation, the leaves were rinsed with running water. The number of leaf lesions was recorded 3 days after inoculation, and the control effect was calculated.

[0036] 4. In vivo therapeutic effects:

[0037] Selected 3–5 leaf stage *Nicotiana sambac* plants with uniform growth were inoculated with a 10 µg / mL virus solution using a paintbrush. The leaves were rinsed with running water and allowed to air dry. Subsequently, a whole-plant spray was applied, with each treatment replicated three times. A 1‰ Tween-80 aqueous solution was used as a control. The number of lesions was assessed and recorded three days after inoculation to calculate the control effect.

[0038] 5. In vivo passivation effect:

[0039] Select uniformly growing 3–5 leaf stage *Nicotiana sambac*. Mix the pesticide with an equal volume of virus sap and inactivate for 30 min, then inoculate by friction. The virus concentration is 20 µg / mL. Rinse immediately with running water after inoculation. Repeat 3 times. Include a 1‰ Tween 80 aqueous solution as a control. Count the number of lesions after 3 days and calculate the results.

[0040] Inhibition rate (%) = [(Number of control necrotic spots - Number of treated necrotic spots) / Number of control necrotic spots] × 100%

[0041] First, the in vivo inactivation activity against tobacco mosaic virus (Tobacco Mosaic Virus) of all compounds was tested at a treatment dose of 500 µg / mL. Compounds with a relative inhibition rate greater than 50% were further tested for in vivo therapeutic and protective activity at a treatment dose of 500 µg / mL, and for in vivo inactivation, therapeutic, and protective activity against Tobacco Mosaic Virus at a treatment dose of 100 µg / mL. The positive control was the commercially available antiviral agent ribavirin.

[0042] Table 1. Results of anti-Tobacco Mosaic Virus (TMV) activity tests of 7 azaindole compounds I-1–I-5:

[0043]

[0044] As shown in Table 1 above, compounds I-1–I-5 of the 7-azaindole class exhibited good antiviral activity against tobacco mosaic virus. Most compounds showed superior antiviral activity compared to the control drug ribavirin, and compound I-4 showed better antiviral activity than ningnanmycin, currently the most effective antiviral agent. Therefore, the 7-azaindole class has the potential to be developed into antiviral agents.

[0045] Example 5: Antibacterial activity test, the measurement procedure is as follows:

[0046] In vitro sterilization test, bacterial growth rate determination method (plate method): A quantitative amount of the drug was dissolved in an appropriate amount of acetone and diluted to the target concentration with an aqueous solution containing 200 µg / mL emulsifier. Then, 1 mL of different concentrations of drug solution and 9 mL of culture medium were added to each petri dish, and the mixture was thoroughly shaken to prepare a drug-containing plate with a final concentration of 50 µg / mL; a plate with 1 mL of sterile water was used as a blank control. Using a 4 mm diameter sterile punch, a bacterial disc was cut along the edge of the colony of the tested strain and inoculated into the center of the drug-containing plate. Each treatment was repeated three times. All petri dishes were placed in a constant temperature incubator at 24±1℃ and incubated in the dark. After 48 hours, the expansion diameter of the colonies in each treatment was measured and the average value was calculated. The relative inhibition rate was calculated by comparing with the blank control.

[0047]

[0048] Table 2.7 Results of anti-plant pathogen activity tests of azaindole compounds I-1–I-5:

[0049]

[0050] As shown in Table 2, at a concentration of 50 μg / mL, all seven-azaindole compounds I-1–I-5 exhibited inhibitory activity against the eight tested pathogens. Compound I-4 showed excellent antibacterial activity against multiple pathogens. These results indicate that seven-azaindole compounds have good development potential.

[0052] The present invention has been described above by way of example. It should be noted that any simple modifications, alterations or other equivalent substitutions that can be made by those skilled in the art without creative effort without departing from the core of the present invention fall within the protection scope of the present invention.

Claims

1. A class of 7-azaindole compounds I, specifically one of the compounds shown in I-1–I-5: 。 2. The method for preparing I-1–I-5 in claim 1: In an acetonitrile solution of sodium hydroxide, 80 o Under C conditions, compounds 1 and 2 undergo nucleophilic substitution to give the corresponding compounds I-1-I-5.

3. The application of the 7-azaindole compounds I-1–I-5 as described in claim 1 in the prevention and control of plant viral diseases, characterized in that, The plant virus in question is tobacco mosaic virus.

4. The application of the 7-azaindole compounds I-1-I-5 as described in claim 1 in the prevention and control of plant pathogenic diseases, characterized in that... The plant pathogens mentioned are apple ring rot fungus, wheat sheath blight fungus, tomato early blight fungus, rice blast fungus, pepper phytophthora, or rapeseed sclerotinia.

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